Safety and delay arming device



SAFETY AND DELAY ARMING DEVICE Filed Dec. 17, 1956 l9 le Q) Q INVENTORS 3| 25 Y A. E. MARTIN 2 E. H. MULLINS BY i369 ATTORNEYS United States SAFETY AND DELAY ARMING DEVICE Albert E. Martin and Elwood H. Mullins, Silver Spring,

Md., assignors to the United States of America as represented by the Secretary of the Navy Application December 17, 1956, Serial No. 628,943

7 Claims. (Cl. 10270.2)

(Granted under Title 35, US. Code (1952), sec. 266) V The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to a safety arming device, and more particularly to a delay safety and arming device for a fuze to be utilized in a spin type ordinance vehicle, such for example, as a missile, projectile or the like.

Although safety and delay arming devices have been heretofore devised and utilized in the ordnance fuze art, the majority of these devices have been of comparatively complicated, bulky and expensive design. Moreover, some of the prior art mechanisms, such as clock timing devices, have not performed entirely satisfactorily due to the difiiculty of making the required adjustments to the complicated mechanisms in the field by relatively unskilled personnel.

Accordingly, -a foremost object of the present invention is to provide a new and improved simple, compact and inexpensive safety and arming device.

Another object of the present invention is to provide a novel safety and arming mechanism for use in ordance applications requiring a minimum of critical wartimematerials, manpower and construction facilities.

A further object of the present invention is to provide a new and improved delay arming device wherein the delay period may be facilely readily varied.

A still further object of. the present invention is to provide a novel centrifugally actuated safety and arming device for use in an ordance fuze.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

Fig. l is a plan view of a preferred form of the novel safety and arming device of the present invention in an initial unarmed position;

Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1;

Fig. 3 is a plan view of the device of Fig. 1 in an armed position; and

Fig. 4 is a plan view of an alternative arrangement of the novel safety and arming according to the present invention.

Referring now to the drawing wherein like reference numerals indicate like parts throughout the several views, and more particularly to Fig. 1 whereon the safety and arming device for use in spin type ordnance vehicle according to thepresent invention is indicated generally by the reference numeral 11. The arming device 11 includes a circular casing 12 composed of any material suitable for the purpose such, for example, as brass, steel or the like, and having an annular recess 13 formed therein. Rotatably disposed Within recess 13 is an inertial member, or rotor 14, composed of any material suitable for the purpose such, for example, as brass or the like, and having an aperture 15 provided therein for ice maintaining the rotor in an unbalanced inertial relation with respect to the axis of rotation thereof about pivot pin 16. Arranged within an opening 17 of the rotor member 14 is a detonator, or primer18.

Engaging a peripheral recess 19 of rotor 14 is a detent, or protuberance 21 formed upon a cantilever arm 22 which may be composed of phenolic or any like insulating material suitable for the purpose. As more clearly shown on Fig. 2, cantilever arm 22 is spring loaded by means of resilient member or spiral spring 23 disposed about pivot pin 24 for maintaining seating of detent 2 1 within rotor recess 19. It will be understood that spring urged arm 22 will maintain the rotor 14 locked in its unarmed or initial position, as shown in Fig. 1, whereby primer 18 will be out of alignment with a flash channel, or lead in charge, 25 provided in casing 12. Arming rotor 14 will be maintained in its unarmed position until the spin or rotational speed of the missile wherein the device 11 is disposed, generates a predetermined amount of centrifugal force to overcome the retaining effect of spring 23 upon arm 22, whereupon detent 21 is withdrawn from recess 19 and rotor 14 is released from its initial position. Although released from its initial position rotor 14 is prevented from rotational movement to an armedposition by means of restraining cord 26 secured to the rotor and casing by any suitable method such, for example, as screws. 27. Cord 26 may be composed of any material suitable for the purpose, such for example as cotton, nylon or the like.

Cord 26 restricts the rotational movementof the arming 'rotor 14 until the spin developed centrifugal force eifects engagement of a heater wire 28, extending between electrodes 29 formed on cantilever arm 22, with cord 26, whreupon the cord is severed as by melting or burning therethrough. Severance of cord 26 will allow for rotation of the arming rotor under the influence of centrifugal force developedby the spinning projectile until the rotor 14 abuts stop pin 31 whereupon the rotor will be in its armed position and pr-imer18 aligned with flash channel 25, as shown in Fig. 3. Y

For the purpose of ensuring engagementof heater-.28 with cord 26, a well 32 may be provided within the casing 12 wherein an extended portion 33 of arm 22 may be arranged 'for securing of lower heater wire electrode 29, as more clearly shown in Fig. 2.

An electrical energy source, such as battery 34 is provided for effecting heating of the filament wire 28. As shown in the drawing, the electrical circuit from battery 34 to heater wire electrodes 29 is formed by wires 35 and 36 connected to a ground terminal 37 on casing 12 and the lower electrode 29 on arm 22, respectively. A combination guide and ground post 38 is provided on casing 12 for effecting the required spatial positioning of cord 26 relative to heater element 28 and for serving as an electrical ground connecting for the upper heater wire electrode 29. For the purpose of delaying energization of heater wire 28 until use of the device 11 is contemplated, a set back or spin actuated switch 39 may be provided in the electrical circuit to battery 34.

In the alternative embodiment of the novel device according to the present invention, shown in Fig. 4, a centrifugally responsive inertial member 41 is substituted in place'of cantilever arm 22 within well 32. As shown, inertial member 41 is urged inwardly toward the rotor 14 by the action of spiral spring 42 whereby a detent 43 formed thereon is seated within the peripheral recess 19 of rotor 14 thereby maintaining the rotor in an initial unarmed position. In this arrangement, the heater wire 28 is positioned between electrodes 29, formed on vertical or raised insulating member 44'secured upon inertial member 41, in such -a manner as to form a half-loop of predetermined radius about restraining cord 26. To ensure the desired spatial positioning of cord 26 within loop heater wire 28 a pair of guide pins 38 and 45 are discretely positioned upon casing 12. Rotor 14 will be retained in an unarmed condition until member 41 .is moved outwardly in response to a predetermined magnitude of centrifugal force whereupon detent 43 is withdrawn from recess 19 and cord 26 subsequently severed by heater wire 28.

In summary, it should be readily apparent to those versed in the art that the simple safety and arming device of the present invention as herein disclosed provides a large degree of variation in the delay arming period by adjustment of the spatial positioning of restraining cord 26 relative to the heater wire 28 and by variation of the diameter, or composition of the heater wire.

Obviously many modifications'and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed'as new and desired to be secured by Letters Patent of the United States is:

1. A delay arming device for a spin type ordnance vehicle comprising a casing, an arming rotor releasably locked within said casing in an initial safe position and adapted to be released for rotative movement to an armed position in response to centrifugal force, resiliently urged inertial means pivotally arranged on said casing for maintaining said rotor in said initial safe position and for releasing said rotor for rotation from said initial position in response to a predetermined value of centri fugal force, threadlike filamentary means interconnecting said rotor and said casing for restricting rotative movement of said rotor upon release thereof, and electroresponsive means secured to said inertial means for engaging and severing said interconnecting means upon movement of said inertial means in response to said predetermined value of centrifugal force thereby enabling said rotor to rotate to said armed position.

2. A delay arming device according to claim 1 wherein said arming rotor includes a weighted element for enhancing the rotational movement thereof in response to centrifugal force.

i in said electroresponsive means further includes an initial- 7 1y interrupted electrical switch adapted to be selectively rendered uninterrupted.

6. A delay'arming device according to claim 1 wherein said resiliently urged inertial means includes a spring loaded cantilever arm pivotally connected to said housing. 7. A delay arming device for a spin type ordnance vehicle comprising a casing, an arming rotor releasably locked within said casing in an initial safeposition and adapted to be rotated to an armed position in response to centrifugal force, springloaded inertial means operatively connected to said casing for maintaining said rotor in said initial safe position and for releasing the rotor from. said initial position in response to a predetermined value of centrifugal force, means interconnecting said rotor and saidcasing for restricting rotative movement of the rotor upon release thereof, and electroresponsive means secured to said inertial means andsurrounding said interconnecting means for severing said interconnecting means upon engagement therewith, thereby enabling said rotor to rotate to said armed position.

References Cited in the file of this patent UNITED STATES PATENTS 2,458,470 Hafstad Jan. 4, 1949 2,472,366 Brode June 7, 1949 2,485,817 Dike Oct. 25, 1949 2,773,449 Karsberg Dec. 11, 1956 2,775,942 Dell Jan. 1, 1957 FOREIGN PATENTS 606,474 Great Britain Aug. 13, 1948 

